Tiêu chuẩn iso 08295 1995 scan

IS0 INTERNATIONAL STANDARD Dit document mag slechts op een stand-alone PC worden geïnstalleerd Gebruik op een netwerk is alleen toegestaan als een aanvullende licentieovereenkomst voor netwerkgebruik met NEN is afgesloten This document may only be used on a stand-alone PC Use in a network is only permitted when a supplementary license agreement for use in a network with NEN has been concluded Second edition 1995-l o-01 Plastics - Film and sheeting Determination of the coefficients P/as tiques - Film et feuille de frottemen t ~~~ -!JlliS&- - Dk termha of friction Con des coefficients Reference number IS0 82953 995(E) Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 8295: 1995(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies) The work of preparing International Standards is normally carried out through IS0 technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee lnternational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work IS0 collaborates closely with the International Electrotechnical Commission (I EC) on all matters of electrotechnical standardization Draft International Standards adopted by the technrcai committees are circulated to the member bodies for voting Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote International Standard IS0 8295 was prepared by Technical Committee lSO/TC 61, Plastics, Subcommittee SC 11, Products edition cancels and replaces the second This (IS0 8295:1986), which has been technically revised Annex A of this International Standard is for information first edition only IS0 1995 All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized cn any form or by any means, electronic or mechanIcal, lncludlng photocopylng and microfilm, without permission in writing from the publisher International Organization for Standardization Case Postale 56 l Cl-i-121 Geneve 20 l Switzerland Printed In Switzerland Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 INTERNATIONAL Plastics coefficients STANDARD IS0 8295:1995(E) IS0 Film and sheeting of friction Scope 1.1 This International Standard specifies a method for determining the coefficients of starting and sliding friction of plastic film and sheeting when sliding over itself or other substances The method is intended to be used for non-sticky plastic film and sheeting (in the following text, referred to simply as “film”) of up to approximately 0,5 mm thickness 1.2 This test method serves primarily for quality control It does not give a comprehensive assessment of the machinability on packaging or processing machines since other effects, e.g electrostatic charges, air cushion, local rise of temperature and abrasion are, as a rule, involved 1.3 The static frictional force increases as a rule, with the time the surfaces are in contact Therefore, to get comparable results, this time span is specified 1.4 Slip properties are sometimes generated by additives in the plastic material The additives have varying degrees of compatibility with the film matrix They may bloom or exude to the surface and change the slip properties Since these effects are timedependent, measurements on such films have to be related to the age of the film - Determination of the cent edition of the standard indicated below Members of IEC and IS0 maintain registers of currently valid International Standards IS0 291: 1977, Plastics conditioning - Standard atmospheres for and testing Definitions For the purposes of this International following definitions apply Standard, the friction: The resistance that two surfaces lying in contact with each other build up against sliding A distinction is made between static friction and dynamic friction 3.1 3.1.1 static friction: come as a “threshold motion Friction which has to be overvalue” at the onset of sliding dynamic friction: Friction which persists during a sliding motion at a given speed 3.12 3.2 frictional come friction static frictional force F, force: The force necessary to overA distinction is made between the force Fs and the dynamic frictional 3.3 normal force, Fp: The force acting perpendicular to the surfaces in contact Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard At the time of publication, the edition indicated was valid All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- coefficient of friction: The ratio of the frictional 3.4 force to the normal force, acting perpendicular to the two surfaces in contact 3.4.1 static coefficient of friction: FS Ps = -jyP Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 @aIS0 8295: 1995(E) 3.42 dynamic & of friction: Figure I shows an example of apparatus in which table is moved horizontally The vertical motion tensile tester may also be utilized; in this case, test table is fixed to the crosshead of the machine the force is deflected to the horizontal direction pulley of films The force is recorded by a chart recorder or an equivalent electrical data-processing unit coefficient FD = F P NOTES The coefficient tween 02 and of friction usually ranges be- Ideally, the coefficient of friction is a characteristic independent of the test equipment and the test conditions Since films generally not behave ideally, all test parameters are specified in this International Standard 5.2 The test device shall comply with the following conditions Principle 52.1 The surface of the test table shall be flat and smooth, and made of a non-ferromagnetic metal The surfaces to be tested are placed together in plane contact and under uniform contact pressure The force needed to displace the surfaces relative to each other is recorded the of a the and by a 52.2 The normal force shall be generated by a sled with a square-shaped contact base of 40 cm* (edge length 63 mm) To ensure uniform pressure distribution, the base of the sled shall be covered with an elastic material, for example felt The structure of this covering material shall be fine enough to avoid embossing thin films The total mass of the sled shall be 200 g & g (exerting a normal force of I,96 N -+ 0,02 N) Apparatus The test device may be constructed in different 5.1 ways In general, it consists of a horizontal test table, a sled, and a driving mechanism to produce a relative motion between the sled and the test table, regardless of which is the moving part D C F B E G A H B G Sled Test specimens Moving table Load cell Reinforcement plate Spring Double-faced adhesive tape Felt Figure - Example of moving-table apparatus for determination of coefficients of friction Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 IS0 8295: 1995(E) 52.3 The motion that induces the friction process shall be free of vibrations and shall normally have a speed of 100 mm/min + 10 mm/min Unless otherwise specified, the long axis, and thus the test direction, shall be parallel to the machine direction of the film In the case of specialist films or where difficulties are encountered, a speed of 500 mm/min + 10 mm/min may be used This shall be reported in clause 11, item f) When different frictional properties are expected for the two surfaces, front (I) and back (Z), the two surfaces shall be identified and tested l/l, 2/Z and/or l/2 as agreed between the interested parties The force-measuring system, including the recording instrument, shall not exceed an error of & % Its transition time fg9 Y0 shall not exceed 0,5 s The pulling direction shall be in straight alignment with the frictional plane 5.2.4 If the force-measuring system of a tensile tester is used, the transition time tg9 Y0 shall be particularly checked, as the indicating systems of these machines are often rather inert 5.2.5 For the measurement of the static friction, the friction drag of the force-measuring system shall be adjusted to N/cm + N/cm This may be accomplished by using a suitable spring For the measurement of the dynamic friction in the case of slipstick behaviour, this spring shall be replaced by a rigid connection The inertia of the mass of the sled induces an NOTE additional force at the start of the sled movement; thus the coefficient of friction differs from its true value by an amount A grven by Extreme care shall be taken in handling the samples and specimens The test surfaces shall be kept free of dust, fingerprints or any foreign matter that might change the surface characteristics NOTES Testing of three pairs of test specimens represents a minimum for estimating the statistical tolerance interval Depending on the intended precision and the homogeneity of the material under test, the number of specimens tested may have to be increased IS0 2602:1980, Statistica/ inferpretation of test results - Estimation of the mean - Confidence interval, gives guidance in this respect To avoid contamination of the surfaces, several test specimens may be cut simultaneously and separated immediately before testing Unless otherwise specified, specimens shall be conditioned for at least 16 h in standard atmosphere 23/50 as defined in IS0 291 prior to testing V is the speed of the sled relative to the table ( = 100 mm/min); m is the mass of the sled (= 200 g); s is the acceleration (= 810 mm/s*); II due to Procedure The following directions refer to an apparatus designed in accordance with figure If another equivalent apparatus is used, the appropriate procedure shall be followed The testing shall be carried out in the same atmosphere as used for conditioning gravity 8.1 Measurement of film against film is the friction drag (2 N/cm = x O5 g/s2) Under these conditions, the overshoot of the coefficient of friction is 0,005 In the worst case, this means that, at a low coefficient of friction of 0,2, the overshoot equals an error of 2,5 % Conditioning Test specimens For each measurement, two test specimens measuring about 80 mm x 200 mm are needed At least three such pairs of test specimens taken from points uniformly distributed over the width of the sample, or the cjrcumference in the case of tubular film, shall be tested Fix the right-hand end of the first test specimen on the test table with double-faced adhesive tape (or by a suitable clamp) so that the length axis of the test specimen coincides with that of the table Reinforce the left-hand end of the second test specimen by attaching a small plate to it with double-faced adhesive tape The mass of this plate shall not exceed g Connect this plate via a spring (see 5.2.5) to the load cell Lay the second test specimen on the first and place the sled on top, gently and without shock, in the middle of the second test specimen (for films producing high blocking or other than frictional forces the contact area, i.e the size of the upper test specimen shall be reduced as closely as possible to the 8.1.1 Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 8295: 1995(E) IS0 area of the sled) Before starting the test, the apparatus shall be free of stress After 15 s, start the motion of the test table and start up the recording instrument The first force peak is caused by static friction After the first peak, oscillations in the force may sometimes occur In this case, the oscillating part of the graph cannot be used to determine the dynamic coefficient of friction The dynamic coefficient shall be determined by a separate measurement in which slipstick behaviour is eliminated by replacing the spring with a rigid connection calculated, but not the static coefficient The static coefficient equation of film material in contact with If the frictional behaviour of a film in contact with a metal surface or the surface of another material is to be determined, the lower test specimen (see figure 1) shall be replaced by a specimen of the material in question Otherwise, the same procedure shall be used The coefficients of friction determined in this way are dependent on the type of material as well as on its surface finish FS 9.2 9.1 Static force, expressed Dynamic coefficient in by the mass in newtons of friction The frictional force acting during the sliding motion often differs from the constant value which would exist in an ideal situation due to secondary effects related to increasing path length The dynamic frictional force F, is the average force over the first cm of movement after the start of relative movement between the surfaces in contact, neglecting the static force peak F, The dynamic coefficient of friction IUDis calculated from the dynamic frictional force using the equation FD = F P & where FD F, 10 Expression is the static frictional newtons; is the normal force exerted of the sled, expressed (= I,96 N) If subsequent measurements are made on the same test specimen of a material, it should be noted that abrasion may have occurred, which will change the surface properties Also, the possibility of transfer of slip or antislip agent shall be considered ps is given by the where This type of determination cannot be used to determine the static coefficient of friction because of the inertia error (see note in 52.5) 8.2 Measurement metal or another of friction FS Ps = P 8.12 NOTE The load cell may also be attached directly to the sled In this case, the second test specimen is fastened to the front edge of the sled with double-faced adhesive tape However, this procedure is not advisable for stiff films since the bending moment may cause an unequal pressure distribution of friction (see 8.12) is the dynamic rn newtons; frictional force, expressed is the normal force exerted of the sled, expressed (= I,96 N) by the mass in newtons Precision of results coefficient of friction The force increases linearly to a maximum which represents the static frictional force Fs Measurements made at a high friction drag (i.e without a spring) permit the dynamic coefficient of friction to be The dispersion of the coefficients of friction of several plastics has been investigated in a preliminary interlaboratory trial intended, first and foremost, to assess an alternative test speed, and also to provide preliminary precision data (see annex A) When further repeatability and reproducibility data are obtained, they will be added at the following revision” Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 CJIS0 11 SO 8295:1995(E d) Test report The test report shall include the following a) a reference to this International particulars: the individual and average vail es and, if required the standard deviation and the number of tests for 1) the static coefficient Standard; of friction, 2) the dynamic coefficient of friction; b) all information necessary for identification of the plastic film sample, and, if known, the approximate age of the film; e) if measurements were made with the film in contact with other materials, an exact description of these surfaces; c) f) any deviations from this International which of the two surfaces was tested; Standard Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 8295: 1995(E) Annex A (informative) Preliminary precision A preliminary inter-laboratory trial was carried out in ‘l993 to verify whether a test speed of 500 mm/min can be used instead of 100 mm/min for plastics having a high coefficient of friction which may cause insufficient precision of the results The trial was conducted not only to assess the alternative test speed, but also to acquire preliminary precision data The precision data obtained show that a test speed of 100 mm/min is suitable for all the materials tested in the trial The trial was organized and the results analysed in accordance with IS0 5725-l, IS0 5725-2 and IS0 5725-3l) and involved four laboratories (in China, France, Japan and the UK) and four samples of which both the internal and external surfaces were tested Although the number of participating laboratories did not satisfy the requirements of IS0 5725, tables A.1 Table A.1 - Precision data and A.2 have been prepared from selected data as useful examples, pending a full-scale precision trial to be conducted before the next revision The data are arranged in order of magnitude and classified by coefficient of dynamic and coefficient of static friction To make it easier to compare the standard deviations between the levels, with no regard to the absolute values, the coefficients of variation have been calculated and included in parentheses in tables A.1 and A.2 coefficient of variation (%) standard deviation = No outliers were detected of dynamic coefficient I/E friction between friction between 100 by Grubb’s test of friction Plastics (Nominal thickness in pm), surface/surface l/l x average coefficient of friction deviation, sR internal surface and internal surface; internal surface and external surface 1) IS0 5725-I : 1994 Accuracy (trueness and precision) of measurement definitions methods and results - IS0 5725-23 994, Accuracy (trueness and precision) of measurement methods and results determination of repeatability and reproducibility of a standard measurement method IS0 5725-3:1994 Accuracy (trueness and preclslon) of measurement of the precision of a standard measurement method methods and results - Part I: General principles and Part 2.* Basic method Part 3: IntermedIate for the measures Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 8295: 1995(E) Table A.2 Plastics (Nominal thickness in pm), surface/surface - Precision (60) PVC PE-LL PC l/l (ZAO, I l/l (30) , (100) I I/E l/l l/E friction between Reproducibility standard deviation, SR (Coefficient of variation) (12,6 %) 0,077 (27,8 %) (16,O %) 0,100 (II,7 of variation) 0,277 0,035 0,857 0,136 0,765 0,173 (22,7 %) 0,207 (27,l 0,612 0,042 (6,9 %) 0,037 (6,l 0,105 (18,18 0,096 (14,55 %) I %) %) %) %) internal surface and internal surface; friction between internal surface and external surface The dynamic and static data were taneously in the same test run obtained simul- The inter-laboratory trial was carried out not only to obtain precision data but also to improve the test method The data obtained and many of the observations made during the test were of considerable interest They will be considered at the next revision with the arm of improving the method The following comments are particularly worth noting: (i) of friction (Coefficient Average l/l coefficient Reproducibility-withinlaboratory standard deviation, sRW Average coefficient (n= 5) PP of static Condition of sample The average reproducibility-within-laboratory standard deviations sRw given in the tables are nearly the same as the reproducibility standard deviations +, and in some instances sR is less than sRW These data are unusual because SRw is usually approximately onethird of + The data suggest either that the measurements can fluctuate greatly due to the various factors encountered, or that the specimens tested were not identical The samples were distributed from a single source and were identical but, judging from the reports of the state of the samples received and tested by some laboratories, it is doubtful that the specimens used in each laboratory were strictly identical Some samples were reported to have had surfaces which were not flat, or even creased These samples should not, of course, have been used for testing The condition of the sample should therefore be described in much more detail in the test report (ii) Static electricity It was reported that, in some specimens, static charge was observed during testing, which made it difficult to handle the specimens properly The effect of static charge should be investigated, but it is suggested in any case that the static charge should be eliminated before testing (iii) Measurement of frictional force The recorded plots of the static frictional force varied from lab to lab Some were rather flat while some showed curves which rose as the test proceeded It is possible that the operators have interpreted these plots differently, thus giving values which vary more widely than expected The system of measuring, recording and calculating the average frictional force should therefore be investigated in detail in order to reduce the variation in the data (iv) Sled material and weight of sled These two factors affect the actual contact area between the surfaces of specimens Stiff films tend to have a smaller contact area, and hence the pressure is less uniform, when the sled is not heavy enough This aspect may well be worth studying This International Standard requires that the sled be covered with an elastic material The sled and the elastic material used should be defined as specifically as possible in order to keep the pressure uniform and obtain more reproducible results Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 IS0 8295:1995(E) (v) The spring The spring, intended to control the initial speed of the sled to give even acceleration, could not be used in the case of high-friction film such as PE-LLD, because no spring was available which met the requirements of the standard The sled was therefore connected directly to the load cell, and the value obtained depended on the apparatus used, different apparatus giving a different initial acceleration The values of the dynamic coefficient of friction obtained are only relative values IS0 NOTES Reproducibility is the precision under conditions in which the test results are obtained using the same method and identical test material but in different laboratories with different operators using different equipment, and are expressed in terms of the reproducibility standard deviation Reproducibility-within-laboratory is the precision under conditions in which the test results are obtained in the same laboratory using the same method and identical test material, but the operator, the equipment and/or the time of measurement may be different Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 This page intentionally left blank Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25 c-?IS0 IS0 8295: 1995(E) ICS 83.140 Descriptors: plastics, films, sheets, tests, friction tests, determination, friction factor, test equipment Price based on pages Dit document is door NEN onder licentie verstrekt aan: / This document has been supplied under license by NEN to: Eurotech Benelux B.V M Boom 2007/02/25